Cholinesterase as a predictor of skeletal muscle loss after gastrectomy for gastric cancer.

BACKGROUND: Cholinesterase is a classical nutritional and inflammatory marker. The aim of the present study was to evaluate the value of cholinesterase as a predictive marker for postoperative skeletal muscle loss after gastrectomy for gastric cancer. METHODS: The study comprised 68 patients who had undergone gastrectomy for gastric cancer. Skeletal muscle mass was evaluated using skeletal mass index, and major skeletal muscle loss was defined as less than or equal to the median change rate (1-year postoperative/preoperative) of skeletal mass index in all patients. We explored the relationship between postoperative major skeletal muscle loss and disease-free survival and overall survival. Then we investigated the relationship between change rate of skeletal muscle index and serum cholinesterase levels after gastrectomy. RESULTS: The median value of change rate of skeletal mass index was 0.93. Postoperative major skeletal muscle loss was significantly associated with disease-free survival after gastrectomy (P = 0.003). Although major skeletal muscle loss had worse overall survival, it was not significant (P = 0.058). The change rate of skeletal mass index and cholinesterase had a stronger positive correlation compared with other nutritional indices according to Spearman's rank correlation coefficient (r = 0.438, P ≤ 0.001). CONCLUSION: Evaluation of serum cholinesterase levels may be valuable for predicting postoperative skeletal muscle loss after gastrectomy, suggesting the importance of cholinesterase in postoperative nutritional management of patients with gastric cancer.

Cachexia Index in Patients with Gastrointestinal Cancer: A Systematic Review and Meta-Analysis.

PURPOSE: The cachexia index is a novel biomarker of cancer cachexia. This systematic review and meta-analysis aimed to evaluate the prognostic impact of cachexia index on prognosis after surgery for gastrointestinal cancer. METHODS: In August 2023, we systematically searched PubMed, the Cochrane Library, and Ovid for relevant studies on the oncological outcome after gastrointestinal cancer surgery and analyzed the findings from these studies for meta-analysis. RESULTS: Our systematic and meta-analysis review identified eight studies involving 1876 patients. The number of patients with low cachexia index accounted for 813 patients (43.3%). We found that low cachexia index was associated with worse overall survival (pooled HR, 2.30; 95% CI, 1.85-2.87; z = 7.49; P < 0.001) and disease/relapse/progression-free survival (pooled HR, 1.77; 95% CI, 1.45-2.18; z = 5.50; P < 0.001). CONCLUSION: Our meta-analysis showed that cachexia index was associated with oncological outcome after gastrointestinal cancer surgery. However, the limitations of this meta-analysis should be taken into consideration when interpreting the results.

Association of Cholinesterase With Postoperative Pneumonia After Gastrectomy for Gastric Cancer.

INTRODUCTION: Cholinesterase is a classical marker that reflects nutritional and inflammatory status. The aim of the present study was to evaluate the association between serum cholinesterase levels and postoperative infectious complications in patients undergoing gastrectomy for gastric cancer. MATERIALS AND METHODS: This retrospective study comprised 108 patients who underwent gastrectomy for gastric cancer. We comprehensively investigated the association between clinicopathological variables and postoperative infectious complications after gastrectomy. Then patients were divided into the cholinesterase-high and -low groups to analyze their clinicopathological variables. Finally, we analyzed the types of infectious complications that were most associated with preoperative serum cholinesterase levels. RESULTS: Twenty-six patients (24%) developed postoperative infectious complications. Multivariate analysis revealed that serum cholinesterase levels (P = 0.026) and N stage (P = 0.009) were independent risk factors for postoperative infectious complications. In particular, the incidence of pneumonia (P = 0.001) was significantly higher in the cholinesterase-low group. Age (P = 0.023), cerebrovascular comorbidities (P = 0.006), serum cholinesterase levels (P = 0.013), and total gastrectomy (P = 0.017) were identified as independent risk factors for postoperative pneumonia. CONCLUSIONS: Preoperative serum cholinesterase levels were associated with postoperative pneumonia after gastrectomy for gastric cancer, suggesting the importance of preoperative nutritional assessment in gastric cancer surgery.

Indocyanine Green Fluorescent Lymphography During Open Inguinal Hernia Repair: Relationship Between Lymphatic Vessel Injury and Postoperative Hydrocele.

BACKGROUND: This prospective case series analyzed patients who underwent indocyanine green (ICG) fluorescent lymphography during open inguinal hernia repair. The aim of this study was to investigate the association between ICG leakage and postoperative hydroceles in patients who underwent inguinal hernia repair. MATERIALS AND METHODS: Data were analyzed from 40 patients who underwent primary open hernia repair between October 2020 and June 2021 (44 cases in total). Hydroceles were categorized into two types: symptomatic and "ultrasonic" (detected only by ultrasound imaging). RESULTS: In the univariate analysis, hernia type (p = 0.044) and ICG leakage (p = 0.007) were independent risk factors for postoperative ultrasonic hydroceles. Additionally, mesh type (p = 0.043) and ICG leakage (p = 0.025) were independent risk factors for postoperative symptomatic hydroceles. In the multivariate analysis, ICG leakage (p = 0.034) was an independent risk factor for postoperative ultrasonic hydroceles. CONCLUSIONS: ICG leakage after inguinal hernia repair was independently associated with postoperative ultrasonic and symptomatic hydroceles. These findings suggest a relationship between lymphatic vessel injury and the incidence of postoperative hydroceles.

Short-term outcomes of colorectal cancer surgery in patients with dialysis: a systematic review and meta-analysis.

PURPOSE: This systematic review and meta-analysis aimed to evaluate the effect of dialysis-dependent chronic kidney disease (CKD) on postoperative complications in colorectal cancer surgery. METHODS: In April 2023, we systematically searched PubMed, the Cochrane library, and Ovid for relevant studies on short-term outcomes of colorectal cancer surgery in patients with dialysis and analyzed the findings from these studies for meta-analysis. RESULTS: Our systematic and meta-analysis review identified seven studies involving 50713 patients. We showed that the dialysis group had higher rates of mortality (OR = 4.12, 95%CI: 2.75-6.20, P < 0.001), cardiac complications (OR = 2.45, 95%CI: 1.88-3.21, P < 0.001), and pneumonia (OR = 2.68, 95%CI: 1.83-3.93, P < 0.001). On the other hand, there were no differences in superficial/deep surgical site infection (SSI) (odds ratio [OR] = 1.17, 95%CI: 0.90-1.53, P = 0.230) and organ/space SSI (OR = 1.35, 95%CI: 1.00-1.82, P = 0.053) between the dialysis group and non-dialysis group. CONCLUSION: Our meta-analysis showed that dialysis-dependent CKD was associated with higher rates of mortality, cardiac complications, and pneumonia after colorectal cancer surgery. However, the limitations of this meta-analysis should be taken into consideration when interpreting the results.

The influence of serum cholinesterase levels and sarcopenia on postoperative infectious complications in colorectal cancer surgery.

PURPOSE: Cholinesterase is a nutritional marker associated with sarcopenia. The present study evaluated the relationship between cholinesterase and postoperative infectious complications in patients undergoing colorectal resection for colorectal cancer. METHODS: The study involved 231 patients who had undergone colorectal resection for colorectal cancer. We retrospectively investigated the relationship between preoperative serum cholinesterase levels and postoperative infectious complications. Univariate and multivariate analyses were performed to identify independent risk factors for postoperative infectious complications. We then performed stratified analyses to assess the interaction between cholinesterase and clinical variables to predict postoperative infectious complications. RESULTS: In the multivariate analysis, the body mass index (P = 0.010), serum cholinesterase levels (P = 0.005), sarcopenia (P = 0.003) and blood loss (P < 0.001) were independent risk factors for postoperative infectious complications. In stratified analyses, the association between serum cholinesterase levels and postoperative infectious complications differed by the sarcopenia status (Pinteraction = 0.006). CONCLUSION: Preoperative serum cholinesterase levels may be useful for predicting postoperative infectious complications in colorectal cancer surgery. The association differs by the sarcopenia status, suggesting a potential interaction between nutritional markers and sarcopenia.

Significance of osteopenia in elderly patients undergoing emergency gastrointestinal surgery.

Aim: Frailty assessment in elderly patients is crucial to predict the postoperative course, considering that frailty is highly associated with postoperative complications and mortality. The aim of this study was to evaluate the value of osteopenia as a risk factor for severe postoperative complications in elderly patients who underwent emergency gastrointestinal surgery. Methods: This study comprised 103 elderly patients who underwent emergency gastrointestinal surgery. Osteopenia was diagnosed by measuring bone mineral density, which was calculated as the average pixel density in the midvertebral core at the 11th thoracic vertebra on the preoperative plain computed tomography image. We retrospectively investigated the relationship between preoperative osteopenia and severe postoperative complications (Clavien-Dindo classification ≥III). Univariate and multivariate analyses were performed to evaluate the risk factors for severe postoperative complications. Results: Twenty-three patients (22.3%) developed severe postoperative complications. The optimal cutoff value of bone mineral density for severe postoperative complications was 119.5 Hounsfield unit (HU) and 39 patients (37.9%) were diagnosed with osteopenia. The univariate analysis revealed that the American Society of Anesthesiologists Physical Status of ≥3 (P = .0084), hemoglobin levels (P = .0026), albumin levels (P < .001), sarcopenia (P = .015), and osteopenia (P < .001) were significantly associated with severe postoperative complications. The multivariate analysis showed that osteopenia (P = .014) was an independent risk factor for severe postoperative complications. Conclusion: Osteopenia may be a risk factor for severe postoperative complications in elderly patients after emergency gastrointestinal surgery.

Usefulness of percutaneous transesophageal gastrotubing for gastric outlet obstruction secondary to duodenal ulcer, a case report.

Severe duodenal ulcer stenosis requires continuous decompression, which makes oral ingestion difficult, yet poor nutritional status before surgery increases the risk postoperative complications. Double percutaneous transesophageal gastrotubing (dPTEG) is a new treatment that provides both decompression and enteral nutrition. We report a case of duodenal ulcer scar stenosis in which dPTEG was used for preoperative management. A man in his 40s visited our hospital with vomiting as a chief complaint. CT scan showed duodenal ulcer stenosis. As the existence of malignant disease could not be ruled out, surgery was planned. Before surgery, dPTEG was inserted to achieve decompression and nutritional management. The patient's gastric distension and nutritional status improved significantly, and laparoscopic distal gastrectomy was performed 22 days after the insertion. dPTEG may be an effective management method for patients with pyloric stenosis due to duodenal ulcer.

Nivolumab in combination with radiotherapy for metastatic esophageal neuroendocrine carcinoma after esophagectomy: a case report.

BACKGROUND: Metastatic neuroendocrine carcinoma has an extremely poor prognosis, and no effective second-line treatment is available. Herein, we describe a case of multiple metastases after primary resection of esophageal neuroendocrine carcinoma successfully treated with nivolumab plus radiotherapy in a short time. CASE PRESENTATION: A man in his 70s presented to our hospital after an abnormality was detected on an upper gastrointestinal series. Upper gastrointestinal endoscopy revealed a type 2 tumor spanning the endothelial cell junction to the abdominal esophagus. Histopathological examination of the biopsy confirmed a diagnosis of esophageal neuroendocrine carcinoma. The patient had no distant metastases. Thoracoscopic esophagectomy with three-field lymph node dissection was performed. Histopathological examination confirmed a diagnosis of esophageal neuroendocrine carcinoma with features of adenoid cystic-like carcinoma and squamoid pattern (pT2 [MP], INF a, ly1, v1 [EVG], pIM0, pDM0, pRM0, pN1 [1/28], M0; Stage II), which was positive for synaptophysin. The postoperative course was good, with no complications. The patient was treated with 100 mg of irinotecan and 100 mg of cisplatin, administered every 4 weeks, as postoperative adjuvant chemotherapy. Grade 3 loss of appetite was observed, and adjuvant chemotherapy was discontinued after four cycles of first-line treatment. A positron emission tomography-computed tomography scan 3 years after surgery showed abnormal uptake in the subaortic, left hilar, and left axillary lymph nodes, and in a mass in the right lung apex. The patient was diagnosed with metastatic esophageal neuroendocrine carcinoma postoperatively. First-line treatment could not be repeated due to toxicity from the initial treatment. Nivolumab (240 mg every 2 weeks) was administered as second-line treatment, and radiotherapy was started (56 Gy delivered in 28 fractions to the local [subaortic and hilar] lymph nodes). After 10 cycles of nivolumab in combination with radiotherapy (56 Gy), a positron emission tomography-computed tomography scan showed disappearance of all lesions. A complete response was achieved. Maintenance therapy (240 mg of nivolumab) was continued. No recurrence has been observed for 42 months. CONCLUSIONS: We experienced a case in which nivolumab in combination with radiotherapy was effective for metastatic esophageal neuroendocrine carcinoma after primary resection.

Perineal stapled prolapse resection in combination with Thiersch operation for relapsed rectal prolapse: a case report.

BACKGROUND: Treatment options for complete rectal prolapse include over 100 procedures. In previous reports, operative rectal prolapse repair, regardless of the technique by perineal approach, was associated with high recurrence rates. However, there is no consensus on the optimal surgical procedure for relapsed rectal prolapse. CASE PRESENTATION: A 97-year-old woman was admitted to our hospital with a chief complaint of complete rectal prolapse measuring > 5 cm. The patient had a history of laparoscopic anterior suture rectopexy without sigmoid resection under general anesthesia for complete rectal prolapse one year prior. The patient's postoperative course was uneventful. However, her dementia worsened (Hasegawa's dementia scale: 5/30 points) after the first operation. Further, moderate-to-severe aortic valve stenosis was first diagnosed with heart failure 6 months after the operation. Nine months after the initial surgery, she experienced a recurrence of complete rectal prolapse measuring approximately 5 cm. Considering the coexistence of advanced age, severe dementia, and aortic valve stenosis, surgery under general anesthesia was not indicated. Perineal stapled prolapse resection in combination with the t operation was planned because of its minimal invasiveness and shortened hospital stay. The procedure was performed by a team of two surgeons in the jack knife position, under spinal anesthesia. The prolapse was cut along the long-axis direction with three linear staplers and resected along the short-axis direction with four linear staplers. The cross-section of the linear stapler was reinforced with 3-0 Vicryl sutures. After rectal resection, the Thiersch operation using 1-0 nylon thread 1 cm away from the anal verge was additionally performed. The operative time was 24 min, and intraoperative blood loss was 1 mL. The postoperative course was uneventful. Three months after the operation, no recurrence was observed, and defecation function was good with improvements of Wexner score. CONCLUSIONS: Perineal stapled prolapse resection in combination with the Thiersch operation could be a useful option for patients with relapsed rectal prolapse and with poor general condition, who are not indicated for other surgical procedures.

Minimally invasive colostomy with endoscopy as a novel technique for creation of a trephine stoma.

The conventional approach of trephine stoma creation is associated with various limitations, including poor elevation of the sigmoid colon, misidentification of the target organs, and poor visualization of the operative field, which may require conversion to an open approach. Our study aimed to evaluate the safety, feasibility, and complications of minimally invasive colostomy with endoscopy (MICE), a new technique for trephine stoma creation. This retrospective cohort study included 14 patients. Patients diagnosed with obstructive rectal cancer or bladder and rectal disorders due to spinal cord injury or bone metastasis requiring sigmoid loop colostomy were eligible for the procedure. MICE was performed using a combination of endoscopic and fluoroscopic procedures. The primary endpoint was the technical success of MICE. Technical success using MICE was achieved in all 14 cases. The mean total operative time was 52.6 (range 32-107) min, and mean blood loss was 18.9 (range 1-50) mL. There was no incidence of conversion to open surgery. Postoperative complications included peristomal abscess formation and ischemic colitis in each case. MICE may be useful as a minimally invasive approach for trephine stoma creation that overcomes the problems of a conventional approach in high-risk patients.

Indocyanine green fluorescence-guided laparoscopic colorectal cancer surgery with prophylactic retrograde transileal conduit ureteral catheter placement after previous total cystectomy: a case report.

BACKGROUND: Iatrogenic ureteral injury (UI) is a potentially serious complication of colorectal cancer surgery. Performing perioperative placement of ureteral stents or intraoperative fluorescence navigation surgery for the ureter using indocyanine green (ICG) has been employed as a method of preventing UI. However, transileal conduit stent placement has been considered challenging because it is difficult to identify the ureteral orifice due to the anatomical changes caused by a previous surgery. We report a case in which laparoscopic colectomy was safely performed using a combination of prophylactic transileal conduit ureteral catheter placement and intraoperative ICG fluorescence navigation surgery. CASE PRESENTATION: A 75-year-old man presented to our hospital complaining of vomiting and abdominal distension. He had a history of open total cystectomy and ileal conduit urinary diversion 11 years prior to admission. Computed tomography confirmed colon dilation with fecal impaction from the ascending colon to the sigmoid colon and wall thickening in the sigmoid colon. Colonoscopy during the transanal ileus tube insertion revealed a Borrmann type II tumor with circumferential stenosis 10 cm distal to the junction between the descending colon and the sigmoid colon. The patient was diagnosed with colorectal ileus due to obstructive sigmoid colon cancer and underwent transanal ileus tube insertion. Severe intra-abdominal adhesions were expected due to the previous total cystectomy, and the left ureter was near the sigmoid colon tumor; therefore, prophylactic retrograde transileal conduit ureteral catheter placement was performed one day before the elective surgery. During the operation, 20 ml (5.0 × 10-2 mg/ml) ICG was administered from the transileal conduit ureteral catheter, and ICG fluorescence of the ureter was observed in the retroperitoneum. Laparoscopic Hartmann's operation was successfully performed, confirming ureter fluorescence. The operation time was 231 min, with 5 mL of intraoperative bleeding. The ureteral catheter was removed 3 days after the operation. The patient's postoperative course was good with no complications, and he was discharged on postoperative day 7. CONCLUSIONS: Prophylactic transileal conduit ureteral catheter placement and ICG fluorescence navigation surgery were effective in performing laparoscopic colorectal surgery with severe adhesions after urinary diversion.

Laparoscopic resection of a metachronous secondary lymph node metastasis in the mesentery of the ileum after surgery for sigmoid colon cancer with ileum invasion: a case report.

BACKGROUND: Extended excision of the permeation organ neighborhood is often performed in locally invasive colon cancer, and it is reported to have a survival benefit. In addition, some cases of secondary lymph node metastases in a permeation organ were reported. However, they are reports of synchronous secondary lymph node metastases, not metachronous secondary lymph node metastases. To the best of our knowledge, there are no cases of metachronous secondary lymph node metastases after the resection of a primary colorectal cancer in PubMed. CASE PRESENTATION: The case was a 67-year-old man who underwent colonoscopy because of weight loss. Sigmoid colon cancer with all circumference-related stenosis was found by examination, and the patient was transferred to our hospital for the purpose of scrutiny and treatment. The small intestine ileus caused by the invasion of sigmoid colon cancer developed after the transfer. Laparoscopic high anterior resection and extended excision of small intestine segmental resection was performed after the intestinal tract decompression with a nasal ileus tube. Histopathological analysis revealed a pathological diagnosis of pT4b (ileal submucosal invasion) N0 (0/11) M0 f Stage II, tub2, ly1, v2, PN0. Although adjuvant chemotherapy with capecitabine after the operation was planned for half a year, treatment was suspended in the first course by the patient's self-judgment. No recurrence was observed for a year after the operation, but metastasis recurrence in the para-aortic lymph node was found by a computed tomography (CT) one and a half years after the operation. 18 F-fluorodeoxyglucose (FDG) positron emission tomography revealed that FDG was accumulated only in the para-aortic lymph node. Laparoscopic metastasis lymphadenectomy was performed due to the diagnosis of metachronous metastasis to the para-aortic lymph node alone. Intraoperative findings revealed that lymph node metastasis occurred in the mesentery of the ileum. No adjuvant treatment was done after the secondary operation, and he is still alive with no recurrence 1 year and 9 months after the operation. CONCLUSIONS: We report a rare case of a laparoscopic resection of a metachronous secondary lymph node metastasis in the mesentery of the ileum after surgery for sigmoid colon cancer with ileum invasion.

Laparoscopic resection of a neuroendocrine tumor that almost fully replaced tailgut cysts: a case report.

BACKGROUND: Neuroendocrine tumors (NETs) originate from neuroendocrine cells, which are found throughout the body. NETs occur principally in the gastrointestinal tract (approximately 65%) and bronchopulmonary tract (approximately 25%) but rarely occur in the presacral space. Aside from primary and metastatic lesions, there have been reports of NETs occurring in the presacral space arising from tailgut cysts, teratomas, and imperforate anus. We herein report a rare case of laparoscopic resection of a NET in the presacral space, which almost fully replaced tailgut cysts. CASE PRESENTATION: A 68-year-old woman was referred to our hospital for surgery of a right inguinal hernia, but preoperative computed tomography revealed an asymptomatic 43-mm mass in the presacral space. Magnetic resonance imaging showed a multilocular solid mass with clear boundaries and a slightly high signal intensity on T1- and T2-weighted images. Positron emission tomography showed 18F-fluorodeoxyglucose uptake. Thus, we suspected a malignant tumor and performed laparoscopic resection to obtain a definitive diagnosis. Macroscopically, the tumor was 43 mm in size with clear boundaries, and the cut surface was a gray-white solid component. Histopathological findings revealed that the tumor was composed of relatively uniform cells with fine chromatin, with round to oval nuclei arranged in solid, trabecular, or rosette-like growth patterns. Small cysts lined with stratified squamous epithelium and columnar epithelium were observed along with solid components of the tumor, which is a feature of tailgut cysts. Therefore, the final diagnosis was NET Grade 1 arising from tailgut cysts. No recurrence was observed within 1 year after surgery. CONCLUSIONS: We performed en bloc laparoscopic resection of a NET arising from tailgut cysts in the presacral space without injury. In cases of a solid lesion in the presacral space, not only the primary disease but also the pathological condition with tissue transformation and replacement should be considered, as in this case.

The Genetic Basis of Scale-Loss Phenotype in the Rapid Radiation of Takifugu Fishes.

Rapid radiation associated with phenotypic divergence and convergence provides an opportunity to study the genetic mechanisms of evolution. Here we investigate the genus Takifugu that has undergone explosive radiation relatively recently and contains a subset of closely-related species with a scale-loss phenotype. By using observations during development and genetic mapping approaches, we show that the scale-loss phenotype of two Takifugu species, T. pardalis Temminck & Schlegel and T. snyderi Abe, is largely controlled by an overlapping genomic segment (QTL). A search for candidate genes underlying the scale-loss phenotype revealed that the QTL region contains no known genes responsible for the evolution of scale-loss phenotype in other fishes. These results suggest that the genes used for the scale-loss phenotypes in the two Takifugu are likely the same, but the genes used for the similar phenotype in Takifugu and distantly related fishes are not the same. Meanwhile, Fgfrl1, a gene predicted to function in a pathway known to regulate bone/scale development was identified in the QTL region. Since Fgfr1a1, another memebr of the Fgf signaling pathway, has been implicated in scale loss/scale shape in fish distantly related to Takifugu, our results suggest that the convergence of the scale-loss phenotype may be constrained by signaling modules with conserved roles in scale development.

Effective de novo assembly of fish genome using haploid larvae.

Recent improvements in next-generation sequencing technology have made it possible to do whole genome sequencing, on even non-model eukaryote species with no available reference genomes. However, de novo assembly of diploid genomes is still a big challenge because of allelic variation. The aim of this study was to determine the feasibility of utilizing the genome of haploid fish larvae for de novo assembly of whole-genome sequences. We compared the efficiency of assembly using the haploid genome of yellowtail (Seriola quinqueradiata) with that using the diploid genome obtained from the dam. De novo assembly from the haploid and the diploid sequence reads (100 million reads per each datasets) generated by the Ion Proton sequencer (200 bp) was done under two different assembly algorithms, namely overlap-layout-consensus (OLC) and de Bruijn graph (DBG). This revealed that the assembly of the haploid genome significantly reduced (approximately 22% for OLC, 9% for DBG) the total number of contigs (with longer average and N50 contig lengths) when compared to the diploid genome assembly. The haploid assembly also improved the quality of the scaffolds by reducing the number of regions with unassigned nucleotides (Ns) (total length of Ns; 45,331,916 bp for haploids and 67,724,360 bp for diploids) in OLC-based assemblies. It appears clear that the haploid genome assembly is better because the allelic variation in the diploid genome disrupts the extension of contigs during the assembly process. Our results indicate that utilizing the genome of haploid larvae leads to a significant improvement in the de novo assembly process, thus providing a novel strategy for the construction of reference genomes from non-model diploid organisms such as fish.

Expressed sequence tag analyses of three leukocyte subpopulations in ayu Plecoglossus altivelis altivelis, separated by monoclonal antibodies.

Ayu Plecoglossus altivelis altivelis are one of the most economically important fish for freshwater aquaculture in Japan. We conducted expressed sequence tag analyses of three leukocyte subpopulations, thrombocytes, neutrophils, and B lymphocytes in ayu using a next generation sequencer. The sequencing and de novo assembly yielded 22,494, 22,733, and 16,505 contigs from the thrombocyte, neutrophil, and B lymphocyte cDNA libraries, respectively. Pathways involving endocytosis, phagosomes, and lysosomes, were found in all three cDNA libraries using pathway analysis. The thrombocyte cDNA library contained 2894 unique sequences, including CXC chemokine receptor 4 and MHC class II. Cytokine and cytokine receptor genes such as interleukin (IL)-1ß, IL-8, IL-1 receptor (IL-1R), IL-8RA, and IL-8RB were found among the 3056 unique sequences of the neutrophil cDNA library. Typical B lymphocyte related genes such as B cell linker protein, immunoglobulin (Ig) M, IgD and transforming growth factor ß were found in the 1590 unique sequences of the B lymphocyte cDNA library. In summary, a large number of immune-related genes were identified from the three leukocyte cDNA libraries. Our results represent a valuable sequence resource for understanding the immune system function in ayu.

Second generation physical and linkage maps of yellowtail (Seriola quinqueradiata) and comparison of synteny with four model fish.

BACKGROUND: Physical and linkage maps are important aids for the assembly of genome sequences, comparative analyses of synteny, and to search for candidate genes by quantitative trait locus analysis. Yellowtail, Seriola quinqueradiata, is an economically important species in Japanese aquaculture, and genetic information will be useful for DNA-assisted breeding. We report the construction of a second generation radiation hybrid map, its synteny analysis, and a second generation linkage map containing SNPs (single nucleotide polymorphisms) in yellowtail. RESULTS: Approximately 1.4 million reads were obtained from transcriptome sequence analysis derived from 11 tissues of one individual. To identify SNPs, cDNA libraries were generated from a pool of 500 whole juveniles, and the gills and kidneys of 100 adults. 9,356 putative SNPs were detected in 6,025 contigs, with a minor allele frequency ≥ 25%. The linkage and radiation hybrid maps were constructed based on these contig sequences. 2,081 markers, including 601 SNPs markers, were mapped onto the linkage map, and 1,532 markers were mapped in the radiation hybrid map. CONCLUSIONS: The second generation linkage and physical maps were constructed using 6,025 contigs having SNP markers. These maps will aid the de novo assembly of sequencing reads, linkage studies and the identification of candidate genes related to important traits. The comparison of marker contigs in the radiation hybrid map indicated that yellowtail is evolutionarily closer to medaka than to green-spotted pufferfish, three-spined stickleback or zebrafish. The synteny analysis may aid studies of chromosomal evolution in yellowtail compared with model fish.

Identification of Sex-Linked SNPs and Sex-Determining Regions in the Yellowtail Genome.

Unlike the conservation of sex-determining (SD) modes seen in most mammals and birds, teleost fishes exhibit a wide variety of SD systems and genes. Hence, the study of SD genes and sex chromosome turnover in fish is one of the most interesting topics in evolutionary biology. To increase resolution of the SD gene evolutionary trajectory in fish, identification of the SD gene in more fish species is necessary. In this study, we focused on the yellowtail, a species widely cultivated in Japan. It is a member of family Carangidae in which no heteromorphic sex chromosome has been observed, and no SD gene has been identified to date. By performing linkage analysis and BAC walking, we identified a genomic region and SNPs with complete linkage to yellowtail sex. Comparative genome analysis revealed the yellowtail SD region ancestral chromosome structure as medaka-fugu. Two inversions occurred in the yellowtail linage after it diverged from the yellowtail-medaka ancestor. An association study using wild yellowtails and the SNPs developed from BAC ends identified two SNPs that can reasonably distinguish the sexes. Therefore, these will be useful genetic markers for yellowtail breeding. Based on a comparative study, it was suggested that a PDZ domain containing the GIPC protein might be involved in yellowtail sex determination. The homomorphic sex chromosomes widely observed in the Carangidae suggest that this family could be a suitable marine fish model to investigate the early stages of sex chromosome evolution, for which our results provide a good starting point.

Construction of a high-coverage bacterial artificial chromosome library and comprehensive genetic linkage map of yellowtail Seriola quinqueradiata.

BACKGROUND: Japanese amberjack/yellowtail (Seriola quinqueradiata) is a commonly cultured marine fish in Japan. For cost effective fish production, a breeding program that increases commercially important traits is one of the major solutions. In selective breeding, information of genetic markers is useful and sufficient to identify individuals carrying advantageous traits but if the aim is to determine the genetic basis of the trait, large insert genomic DNA libraries are essential. In this study, toward prospective understanding of genetic basis of several economically important traits, we constructed a high-coverage bacterial artificial chromosome (BAC) library, obtained sequences from the BAC-end, and constructed comprehensive female and male linkage maps of yellowtail using Simple Sequence Repeat (SSR) markers developed from the BAC-end sequences and a yellowtail genomic library. RESULTS: The total insert length of the BAC library we constructed here was estimated to be approximately 11 Gb and hence 16-times larger than the yellowtail genome. Sequencing of the BAC-ends showed a low fraction of repetitive sequences comparable to that in Tetraodon and fugu. A total of 837 SSR markers developed here were distributed among 24 linkage groups spanning 1,026.70 and 1,057.83 cM with an average interval of 4.96 and 4.32 cM in female and male map respectively without any segregation distortion. Oxford grids suggested conserved synteny between yellowtail and stickleback. CONCLUSIONS: In addition to characteristics of yellowtail genome such as low repetitive sequences and conserved synteny with stickleback, our genomic and genetic resources constructed and revealed here will be powerful tools for the yellowtail breeding program and also for studies regarding the genetic basis of traits.